Joint body, manufacturing method for joint body, and manufacturing apparatus for joint body

ABSTRACT

A joint body includes first and second metal members and a joint portion including a welded portion where the first and second metal members are joined together, the welded portion having a line shape. The joint portion includes first and second longitudinal portions and a plurality of connecting portions. The first longitudinal portion has first intersecting portions arranged in a first direction and extends in the first direction. The second longitudinal portion has second intersecting portions arranged in the first direction and extends in the first direction. The welded portion intersects itself at the first and second intersecting portions. The connecting portions are arranged in the first direction. The connecting portions extend in a first direction and connect the first and second longitudinal portions.

TECHNICAL FIELD

The present invention relates to a joint body, a manufacturing methodfor a joint body, and a manufacturing apparatus for a joint body.

BACKGROUND ART

Patent Documents 1, 2 disclose a joint body manufactured by joining twometal members, that is, a first metal member and a second metal member,by laser welding. Patent Document 1 discloses that a welding mark madeby laser welding is one or a plurality of pairs of straight linesparallel to each other. Patent Document 2 discloses that a welding markmade by laser welding includes a plurality of C-shaped portions arrangedin a row, and adjacent C-shaped portions partially overlap each other.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: JP 2001-507993 A (FIGS. 3, 5)

Patent Document 2: JP 2014-015206 A (FIG. 4(f))

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The joint bodies disclosed in Patent Documents 1, 2 are stillsusceptible to improvement in joint strength between the first metalmember and the second metal member. Therefore, such joint bodies are notsuitable for processing by hot stamping (hot pressing), for example.That is, when the joint bodies are each processed by hot stamping, thefirst metal member and the second metal member may partially orcompletely separate from each other due to insufficient joint strength.Further, when an external force is applied to the hot-stamped componentin a collision, the first metal member and the second metal member mayseparate from each other, so that a sufficient reinforcing effect cannotbe obtained.

It is therefore an object of the present invention to increase jointstrength between two metal members that are joined by welding to form ajoint body. It is another object of the present invention to provide amanufacturing method for the joint body and a manufacturing apparatusfor the joint body.

Means for Solving the Problems

Provided according to a first aspect of the present invention is a jointbody including a first metal member, a second metal member placed on thefirst metal member, and a joint portion including a welded portion wherethe first metal member and the second metal member are joined together,the welded portion having a line shape, in which the joint portionincludes a first longitudinal portion extending in a first direction,the first longitudinal portion having first intersecting portionsarranged in the first direction, the welded portion intersecting itselfat the first intersecting portions, a second longitudinal portionlocated apart from the first longitudinal portion in a second directionintersecting the first direction and extending in the first direction,the second longitudinal portion having second intersecting portionsarranged in the first direction, the welded portion intersecting itselfat the second intersecting portions, and a plurality of connectingportions arranged in the first direction, each extending in the seconddirection and connecting the first longitudinal portion and the secondlongitudinal portion.

The joint portion includes the first and second longitudinal portionsextending in the first direction and the plurality of connectingportions extending in the second direction. That is, the joint portioncorresponds to the welded portion that has a line shape and continuouslyextends in both the first and second directions. In other words, thejoint portion corresponds to the welded portion that has a line shapeand is provided extending two-dimensionally, that is, in a planar form.This makes it possible to sufficiently increase the joint strengthbetween the first metal member and the second metal member constitutingthe joint body.

Provided according to a second aspect of the present invention is amanufacturing method for the joint body according to the first aspect.Specifically, provided according to the second aspect of the presentinvention is a manufacturing method for a joint body having a firstmetal member and a second metal member joined together by causing alaser oscillation system to irradiate a surface of the second metalmember placed on the first metal member with laser light to form a jointportion including a welded portion where the first metal member and thesecond metal member are joined together, the welded portion having aline shape, the manufacturing method including moving an irradiationposition of the laser light to cause the joint portion to include afirst longitudinal portion extending in a first direction, the firstlongitudinal portion having first intersecting portions arranged in thefirst direction, the welded portion intersecting itself at the firstintersecting portions, a second longitudinal portion located apart fromthe first longitudinal portion in a second direction intersecting thefirst direction and extending in the first direction, the secondlongitudinal portion having second intersecting portions arranged in thefirst direction, the welded portion intersecting at the secondintersecting portions, and a plurality of connecting portions arrangedin the first direction, each extending in the second direction andconnecting the first longitudinal portion and the second longitudinalportion.

Provided according to a third aspect of the present invention is amanufacturing apparatus for the joint body according to the firstaspect. Specifically, provided according to the third aspect of thepresent invention is a manufacturing apparatus for a joint body having afirst metal member and a second metal member joined together by causinga laser oscillation system to irradiate a surface of the second metalmember placed on the first metal member with laser light to form a jointportion including a welded portion where the first metal member and thesecond metal member are joined together, the welded portion having aline shape, the manufacturing apparatus including an irradiationposition motion unit configured to move an irradiation position of thelaser light to cause the joint portion to include a first longitudinalportion extending in a first direction, the first longitudinal portionhaving first intersecting portions arranged in the first direction, thewelded portion intersecting itself at the first intersecting portions, asecond longitudinal portion located apart from the first longitudinalportion in a second direction intersecting the first direction andextending in the first direction, the second longitudinal portion havingsecond intersecting portions arranged in the first direction, the weldedportion intersecting itself at the second intersecting portions, and aplurality of connecting portions arranged in the first direction, eachextending in the second direction and connecting the first longitudinalportion and the second longitudinal portion.

Effect of the Invention

It is possible for the joint body according to the present invention tohave a sufficient joint strength between the first metal member and thesecond metal member constituting the joint body. With the manufacturingmethod and manufacturing apparatus according to the present invention,it is possible to manufacture such a joint body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example of a joint body manufacturedby a manufacturing apparatus according to a first embodiment of thepresent invention.

FIG. 2 is a plan view of the example of the joint body manufactured bythe manufacturing apparatus according to the first embodiment of thepresent invention.

FIG. 3A is a perspective view of an example of a B pillar manufacturedby processing the joint body by hot stamping.

FIG. 3B is a perspective view of another example of the B pillarmanufactured by processing the joint body by hot stamping.

FIG. 4 is a schematic perspective view of the manufacturing apparatusfor the joint body according to the first embodiment of the presentinvention.

FIG. 5 is a schematic side view of the manufacturing apparatus for thejoint body according to the first embodiment of the present invention.

FIG. 6A is a schematic plan view showing an example of an irradiationpattern of laser light.

FIG. 6B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 6A.

FIG. 7 is a schematic plan view for describing a cutting process.

FIG. 8A is a schematic plan view showing a first alternative of theirradiation pattern of laser light.

FIG. 8B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 8A.

FIG. 9A is a schematic plan view showing a second alternative of theirradiation pattern of laser light.

FIG. 9B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 9A.

FIG. 10A is a schematic plan view showing a third alternative of theirradiation pattern of laser light.

FIG. 10B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 10A.

FIG. 11A is a schematic plan view showing a fourth alternative of theirradiation pattern of laser light.

FIG. 11B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 11A.

FIG. 12A is a schematic plan view showing a fifth alternative of theirradiation pattern of laser light.

FIG. 12B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 12A.

FIG. 13A is a schematic plan view showing a sixth alternative of theirradiation pattern of laser light.

FIG. 13B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 13A.

FIG. 14A is a schematic plan view showing a seventh alternative of theirradiation pattern of laser light.

FIG. 14B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 14A.

FIG. 15A is a schematic plan view showing an eighth alternative of theirradiation pattern of laser light.

FIG. 15B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 15A.

FIG. 16A is a schematic plan view showing a ninth alternative of theirradiation pattern of laser light.

FIG. 16B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 16A.

FIG. 17A is a schematic plan view showing a tenth alternative of theirradiation pattern of laser light.

FIG. 17B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 17A.

FIG. 18A is a schematic plan view showing an eleventh alternative of theirradiation pattern of laser light.

FIG. 18B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 18A.

FIG. 19A is a schematic plan view showing a twelfth alternative of theirradiation pattern of laser light.

FIG. 19B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 19A.

FIG. 20A is a schematic plan view showing a thirteenth alternative ofthe irradiation pattern of laser light.

FIG. 20B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 20A.

FIG. 21A is a schematic plan view showing a fourteenth alternative ofthe irradiation pattern of laser light.

FIG. 21B is a schematic plan view showing an example of a joint portionobtained based on the irradiation pattern shown in FIG. 21A.

FIG. 22 is a schematic perspective view of a manufacturing apparatus fora joint body according to a second embodiment of the present invention.

FIG. 23 is a schematic perspective view of a manufacturing apparatus fora joint body according to a third embodiment of the present invention.

FIG. 24 is a perspective view of an example of the joint bodymanufactured by the manufacturing apparatus according to the thirdembodiment of the present invention.

FIG. 25 is a plan view showing an alternative of the joint body.

MODE FOR CARRYING OUT THE INVENTION First Embodiment

A description will be given below of a first embodiment of the presentinvention with reference to FIGS. 1 to 21B.

Joint Body

FIGS. 1 and 2 show a joint body 1 manufactured by a manufacturingapparatus (FIGS. 4 and 5) according to the first embodiment of thepresent invention.

The joint body 1 shown in FIGS. 1 and 2 includes a blank material 2(first metal member) that is an example of a steel plate and areinforcing material 3 (second metal member) that is also an example ofa steel plate. According to the present embodiment, the reinforcingmaterial 3 is narrower than the blank material 2.

The reinforcing material 3 is placed on the blank material 2 and fixedto the blank material 2 by laser welding. The joint body 1 includes ajoint portion 5 formed by one streak of continuous welding mark orwelded portion 4. The blank material 2 and the reinforcing material 3are joined together along the joint portion 5. The joint portion 5 shownin FIGS. 1 and 2 is merely an example, and, as will be described laterwith reference to FIGS. 8A to 21B, the specific form of the jointportion 5 includes various alternatives.

The joint portion 5 includes a main body 6 and an end portion 7.

According to the present embodiment, the welded portion 4 in the mainbody 6 of the joint portion 5 has a curved shape having a periodicrepetitive pattern and includes a first longitudinal portion 8, a secondlongitudinal portion 9, and a plurality of connecting portions 10 havinga curved shape. In the first longitudinal portion 8, a plurality ofintersecting portions 8 a (first intersecting portions) where the weldedportion 4 intersects itself are arranged in one direction A (firstdirection) in plan view, and the first longitudinal portion 8 itselfextends in the direction A. The direction A coincides with a weldingdirection (see a symbol WD in FIG. 4, for example) to be described laterand a direction opposite to the welding direction. The secondlongitudinal portion 9 is located apart from the first longitudinalportion 8 in a direction B orthogonal to the direction A in plan view.In the second longitudinal portion 9, as with the first longitudinalportion 8, a plurality of intersecting portions 9 a (second intersectingportions) where the welded portion 4 intersects itself are arranged inthe direction A in plan view, and the second longitudinal portion 9itself extends in the direction A. The plurality of connecting portions10 are arranged at intervals in the direction A, each of the connectingportions 10 extends in the direction B, and both ends of each of theconnecting portions 10 are connected to the first longitudinal portion 8and the second longitudinal portion 9. Connecting portions 10 adjacentto each other do not intersect. That is, according to the presentembodiment, the first longitudinal portion 8, the second longitudinalportion 9, and the plurality of connecting portions 10 form aladder-like structure in plan view.

The end portion 7 of the joint portion 5 has a zigzag shape or azigzag-line shape that extends forward and backward, at close intervals,between both ends in a width direction of the reinforcing material 3. Aswill be described later with reference to FIG. 24, the joint portion 5may include only the main body 6 without the end portion 7.

In the main body 6 of the joint portion 5, the welded portion 4 having aline shape continuously extends in two directions orthogonal to eachother, that is, in both the directions A, B, in plan view. In otherwords, in the main body 6 of the joint portion 5, the welded portion 4having a line shape is provided extending two-dimensionally, that is, ina planar form. Such a structure allows at least one streak of weldedportion 4 to be present in plan view within a region having a certainarea in the main body 6 of the joint portion 5. In particular, withinsmall regions near the intersecting portions 8 a of the firstlongitudinal portion 8 and the intersecting portions 9 a of the secondlongitudinal portion 9, a plurality of streaks of welded portions 4 arepresent. The main body 6 of the joint portion 5 having such a structuremakes it possible to sufficiently increase the joint strength betweenthe blank material 2 and the reinforcing material 3. For example, whentwo members are joined together by spot welding, the welded portionincludes a plurality of scattered spots. Further, the welded portionmade even by laser welding may include one or a plurality of pairs ofparallel straight lines, or may include a plurality of C-shaped portionsarranged in a row and adjacent to each other. Compared to any of theabove structures, the main body 6 of the joint portion 5 in which thewelded portion 4 having a line shape continuously extends in both thedirections A, B shown in FIGS. 1 and 2 makes it possible to join theblank material 2 and the reinforcing material 3 with higher jointstrength.

Since the blank material 2 and the reinforcing member 3 are joinedtogether with sufficient joint strength, the joint body 1 is suitablefor processing by hot stamping, and it is thus possible to increasestrength of a produced vehicle frame component against collision. Forexample, FIG. 3A shows an example of a B pillar 12 (an example of thevehicle frame component) manufactured by processing the joint body 1 byhot stamping. In this example, the B pillar including the blank material2 and one sheet of reinforcing material 3 joined to the blank material 2is produced by a method in which the reinforcing material 3 is weldedonly to a portion of the blank material 2 that needs to be reinforced soas to have the joint portion 5 shown in FIGS. 1 and 2 and then moldedintegrally with the blank material 2 by hot stamping. FIG. 3B showsanother example of the B pillar 12 manufactured by processing the jointbody 1 by hot stamping. In this example, two reinforcing members arejoined to the blank material 2, and each of the reinforcing materials 3is joined to a ridge line portion formed by hot stamping.

In order to sufficiently increase the joint strength between the blankmaterial 2 and the reinforcing material 3, it is preferable that, in themain body 6 of the joint portion 5, at least one streak of weldedportion 4 passes through a square region whose side is 2 cm long, forexample.

Manufacturing Apparatus and Manufacturing Method for Joint Body

FIGS. 4 and 5 show a manufacturing apparatus 21 for the joint body 1shown in FIGS. 1 and 2. As will be described later with reference toFIGS. 8A to 21B, the manufacturing apparatus 21 is also capable ofmanufacturing a joint body 1 that is different in structure of the jointportion 5 from the joint body 1 shown in FIG. 1 and FIG. 2.

The manufacturing apparatus 21 includes a table 22 on which the blankmaterial 2 is detachably held by a fixture 22 a. A blank conveyingdevice 23 moves the table 22 and the blank material 2 held on the table22 at a constant speed in a conveying direction CD opposite to thewelding direction WD. The table 22 and the blank conveying device 23serve as a conveying unit according to the present invention.

The manufacturing apparatus 21 includes a hoop supplying device 24. Thehoop supplying device 24 (supplying unit) includes a supplying roll pair24 a. The hoop supplying device 24 unwinds a hoop material 20 wound in acoil shape (that becomes the reinforcing material 3 when the joint body1 is completed) with the roll pair 24 a to supply the hoop material 20onto the blank material 2 held on the table 22. More specifically, thehoop supplying device 24 continuously supplies the hoop material 20 thusunwound in a supplying direction SD that coincides with the conveyingdirection CD of the blank material 2 while pressing the hoop material 20against the blank material 2 obliquely from above. A supplying speed ofthe blank material 2 supplied by the hoop supplying device 24 issynchronized with a conveying speed of the blank material 2 conveyed bythe blank conveying device 23. Further, it is also possible to supplynot only a continuous body wound in a hoop shape or a coil shape, butalso a band material cut in advance to a length of the reinforcingmaterial 3 (second metal member).

The manufacturing apparatus 21 includes a laser oscillation system 25.The laser oscillation system 25 includes components necessary forgenerating laser light, such as a laser oscillation element, a drivecircuit, and an optical system. Laser light 26 emitted downward from thelaser oscillation system 25 is projected onto an upper surface of thehoop material 20 at a position immediately before the hoop material 20is pressed against the blank material 2 by the hoop supplying device 24.In FIG. 4, a symbol P0 denotes an irradiation position of the laserlight 26. According to the present embodiment, the laser oscillationsystem 25 does not move in horizontal and vertical directions.

The manufacturing apparatus 21 includes a turning device 27 (irradiationdirection changing unit). The turning device 27 periodically changes anirradiation direction of the laser light 26 emitted from the laseroscillation system 25. As will be described in detail later, assumingthat the laser oscillation system 25 is not in motion in the weldingdirection WD relative to the blank material 2 and the hoop material 20,the turning device 27 periodically changes the irradiation direction ofthe laser light 26 to move a virtual irradiation position P1 along aclosed figure (a circle as will be described later, according to thepresent embodiment). The blank conveying device 23, the hoop supplyingdevice 24, and the turning device 27 serve as an irradiation positionmotion unit according to the present invention.

The manufacturing apparatus 21 includes a cutting drive device 28. Aswill be described in detail later, the cutting drive device 28 cuts thehoop material 20 by moving, after the hoop material 20 is welded to theblank material 2, the hoop supplying device 24 in the welding directionWD as indicated by an arrow C to apply tension to the hoop material 20.Note that, as described above, a configuration where the band materialcut in advance to the length of the reinforcing material 3 (second metalmember) is used eliminates the need for the cutting drive device 28.

A control device 29 controls, in a centralized manner, operations ofvarious components of the manufacturing apparatus 21 including the blankconveying device 23, the hoop supplying device 24, the laser oscillationsystem 25, the turning device 27, and the cutting drive device 28.

A description will be given below of an operation of the manufacturingapparatus 21, that is, a manufacturing method for the joint body 1performed by the manufacturing apparatus 21.

The irradiation direction of the laser light 26 emitted from the laseroscillation system 25 is periodically changed by the turning device 27.Further, the blank material 2 is moved in the conveying direction CD bythe blank conveying device 23, and the hoop material 20 is continuouslysupplied from the hoop supplying device 24 in the supplying direction SDthat coincides with the conveying direction CD. The movements of theblank material 2 and the hoop material 20 cause the laser oscillationsystem 25 to move relative to the blank material 2 and the hoop material20 in the welding direction WD (opposite to the conveying direction CDand the supplying direction SD). The periodical change of theirradiation direction of the laser light 26 and the movement of thelaser oscillation system 25 in the welding direction WD relative to theblank material 2 and the hoop material 20 change an irradiation positionP0 of the laser light 26 on the upper surface of the hoop material 20.As a result, as described above, the main body 6 of the joint portion 5including the first longitudinal portion 8, the second longitudinalportion 9, and the plurality of connecting portions 10 is obtained.

FIG. 6A shows an irradiation pattern 31 of the laser light 26 accordingto the present embodiment. The irradiation pattern 31 is a closed figurealong which the virtual irradiation position P1 of the laser light 26moves assuming that the laser oscillation system 25 is not in motion inthe welding direction WD relative to the blank material 2 and the hoopmaterial 20. The irradiation pattern 31 according to the presentembodiment has a circular shape. The irradiation pattern 31 is obtainedby causing the turning device 27 to periodically change the irradiationdirection of the laser light 26 emitted from the laser oscillationsystem 25. In FIG. 6A, a symbol MD denotes a direction in which thevirtual irradiation position P1 moves on the irradiation pattern 31according to the present embodiment.

FIG. 6B shows the main body 6 of the joint portion 5 obtained based onthe irradiation pattern 31 having a circular shape shown in FIG. 6A. Ingeneral, the shape of the main body 6 of the joint portion 5 isdetermined based on a geometric shape of the irradiation pattern 31, aspeed Vw at which the laser oscillation system 25 moves in the weldingdirection WD relative to the blank material 2 and the hoop material 20(corresponding to a speed at which the irradiation pattern 31 movesrelative to the blank material 2 and the hoop material 20), and a speedVp1 at which the virtual irradiation position P1 moves on theirradiation pattern 31 to be described later.

According to the present embodiment, the speed Vp1 at which the virtualirradiation position P1 moves on the irradiation pattern 31 is notconstant. Specifically, for regions AR1, AR2 of the irradiation pattern31 that extend approximately orthogonal to the welding direction WD, thespeed Vp1 is set equal to a reference speed Vp1_st (Vp1=Vp1_st). As thereference speed Vp1_st, for example, an average of the speed Vp1 atwhich the virtual irradiation position P1 moves on the irradiationpattern 31 can be used. For a region AR3 of the irradiation pattern 31where the virtual irradiation position P1 moves in the directionapproximately opposite to the welding direction WD, the speed Vp1 atwhich the virtual irradiation position P1 moves is set equal to a speedresulting from adding a correction α (α is a positive number) to thereference speed Vp1_st. (Vp1=Vp1_st+α). This speed Vp1 (=Vp1_st+α)corresponds to a second correction speed according to the presentinvention. On the other hand, for a region AR4 of the irradiationpattern 31 where the virtual irradiation position P1 moves approximatelyin the welding direction WD, the speed Vp1 at which the virtualirradiation position P1 moves is set equal to a speed resulting fromsubtracting the correction α from the reference speed Vp1_st(Vp1=Vp1_st−α). This speed Vp (=Vp1_st−α) corresponds to a firstcorrection speed according to the present invention. As described above,controlling the speed Vp1 at which the virtual irradiation position P1.moves on the irradiation pattern 31 allows a speed Vr at which anirradiation position P0 moves on the main body 6 of the joint portion 5to be maintained within a favorable speed range. That is, the speed Vrat which the irradiation position P0 moves on the main body 6 of thejoint portion 5 is made uniform. As a result, an excellent main body 6of the joint portion 5 having a uniform depth, width, and the like canbe obtained.

The hoop supplying device 24 supplies the hoop material 20 unwound whilepressing the hoop material 20 against the blank 2 obliquely from above.The supplying direction SD of the hoop material 20 supplied from thehoop supplying device 24 coincides with the conveying direction CD ofthe blank material 2, and the supplying speed of the hoop material 20coincides with the conveying speed of the blank 2. That is, relativepositions of the blank material 2 and the hoop material 20 do not move.Accordingly, the hoop material 20 can be fixed to the blank material 2by welding with the laser light 26 emitted from the laser oscillationsystem 25 without being temporarily fixed by a clamp using a fixture orthe like. Further, since this eliminates the need for a fixture or thelike, the entire surface of the hoop material 20 can be irradiated withthe laser light 26. That is, the main body 6 of the joint portion 5 canbe formed on the entire surface of the hoop material 20.

After the main body 6 of the joint portion 5 having a necessary lengthis obtained, the hoop material 20 that is continuous is cut. When thehoop material 20 is cut, the virtual irradiation position P1 isrepeatedly moved forward and backward in a direction orthogonal to thewelding direction WD without interruption of the conveyance of the blankmaterial 2 and the supply of the hoop material 20. As a result, theirradiation position P0 of the laser light 26 moves forward and backwardin a zigzag-line shape at close intervals in a width direction of thehoop material 20 (the direction orthogonal to the welding direction WD),thereby forming the end portion 7 of the joint portion 5. Since thewelded portion 4 having a zigzag-line shape is densely located in theend portion 7, a molten pool before solidification reaches the vicinityof the lower surface of the blank material 2. Immediately after theirradiation with the laser light 26 is stopped, the cutting drive device28 moves the hoop supplying device 24 in the direction indicated by thearrow C (the direction that coincides with the welding direction WD) toapply tension to the hoop material 20. This tension cuts the hoopmaterial 20 at the end portion 7 (see FIG. 7). Of the hoop material 20thus cut, a portion joined to the blank material 2 along the jointportion 5 becomes the reinforcing material 3.

In order to continuously weld the reinforcing material 3 using the hoopmaterial 20, it is necessary to cut the hoop material 20 every time thejoint portion 5 is formed for each sheet of reinforcing material 3.According to the present embodiment, since tension is applied to thehoop material 20 by the cutting drive device 28 to cut the hoop material20 after the formation of the end portion 7 where the welded portion 4is densely located, it is not necessary to provide a mechanical cuttingdevice such as a large cutter and in turn makes it possible to downsizethe manufacturing apparatus 21. Note that means for applying tension tothe hoop material 20 is not particularly limited to any specific means,and means such as a weight or a spring may be employed.

FIGS. 8A, 9A, 10A, 11A, 12A, 13A, 14A, 15A, 16A, 17A, 18A, 19A, 20A, and21A show alternatives of the irradiation patterns 31. FIGS. 8B, 9B, 10B,11B, 12B, 13B, 14B, 15B, 16B, 17B, 18B, 19B, 20B, and 21B each show themain body 6 of the joint portion 5 obtained based on a corresponding oneof the irradiation patterns 31. In these drawings, the same or similarelements as shown in FIGS. 6A and 6B are denoted by the same symbols.

For any of these alternative irradiation patterns 31, the control of thespeed Vp1 at which the virtual irradiation position P1 moves on theirradiation pattern 31 described with reference to FIG. 6A can beperformed. When this control is performed, the speed Vp1 is set equal tothe reference speed Vp1_st for a region of the irradiation pattern 31that extends approximately orthogonal to the welding direction WD.Further, for a region of the irradiation pattern 31 where the virtualirradiation position P1 moves in the direction approximately opposite tothe welding direction WD, the speed Vp1 is set equal to a speedresulting from adding the correction a to the reference speed Vp1_st(Vp1=Vp1_st+α). Further, for a region of the irradiation pattern 31where the virtual irradiation position P1 moves approximately in thewelding direction WD, the speed Vp1 is set equal to a speed resultingfrom subtracting the correction a from the reference speed Vp1_st(Vp1=Vp1_st−α).

The irradiation pattern 31 shown in FIG. 8A has a circular shape, and aradius of the circle gradually increases. As shown in FIG. 8B, in themain body 6 of the joint portion 5 obtained based on this irradiationpattern 31, intersecting portions 10 a are formed where the weldedportion 4 constituting adjacent connecting portions 10 intersectsitself. In other words, in this alternative, a plurality of connectingportions 10 form a grid-like structure. With this irradiation pattern31, even for the reinforcing material 3 whose width varies in alongitudinal direction, it is possible to form the welded portion 4 byirradiating the entire surface with the laser light 26. In contrast tothe case shown in FIG. 8A, the radius of the circular irradiationpattern 31 can be gradually decreased. Further, even with the otherirradiation patterns 31 shown in FIGS. 9A, 10A, 11A, 12A, 13A, 14A, 15A,16A, 17B, 18B, 19A, 20A, and 21A, a gradual increase or decrease inexternal dimension allows the entire surface of the reinforcing material3 whose width varies in the longitudinal direction to be irradiated withthe laser light 26.

The irradiation patterns 31 shown in FIG. 9A has an elliptical shapewhose major axis extends in the welding direction WD. As shown in FIG.9B, in the main body 6 of the joint portion 5 obtained based on thisirradiation pattern 31, the intersecting portions 10 a are also formedwhere the welded portion 4 constituting adjacent connecting portions 10intersects itself. In other words, in this alternative, a plurality ofconnecting portions 10 form a grid-like structure.

The irradiation pattern 31 shown in FIG. 10A has an elliptical shapewhose minor axis extends in the welding direction WD. As shown in FIG.10B, in the main body 6 of the joint portion 5 obtained based on thisirradiation pattern 31, the irradiation pattern 31 also has anelliptical shape, but has a plurality of connecting portions 10 arrangedin the welding direction WD at intervals closer than the intervals ofthe irradiation pattern 31 shown in FIG. 9A.

The irradiation pattern 31 shown in FIG. 11A has a rectangular shapewhose short sides extend in the welding direction WD. As shown in FIG.11B, in the main body 6 of the joint portion 5 obtained based on thisirradiation pattern 31, for example, the first and second longitudinalportions 8, 9 have a shape similar to a geometric straight line ascompared with the irradiation pattern 31 (circular) shown in FIG. 6A.Further, each of the connecting portions has a linear shape.Furthermore, the intersecting portions 10 a are formed where the weldedportion 4 constituting adjacent connecting portions 10 intersectsitself. That is, even in this alternative, the plurality of connectingportions 10 form a grid-like structure.

The irradiation pattern 31 shown in FIG. 12A has an isoscelestrapezoidal shape whose upper base and lower base extend in the weldingdirection WD. As shown in FIG. 12B, in this alternative, both the speedVw at which the laser oscillation system 25 moves in the weldingdirection WD relative to the blank material 2 and the hoop material 20and the speed Vp1 at which the virtual irradiation position P1 moves onthe irradiation pattern 31 are appropriately set, thereby causing thefirst and second longitudinal portions 8, 9 to linearly extend in thewelding direction WD. This further causes the connecting portions 10 tolinearly extend in a direction approximately orthogonal to the weldingdirection WD. The welded portion 4 constituting the connecting portions10 does not intersect itself, and the main body 6 of the joint portion 5forms a ladder-like structure.

The irradiation pattern 31 shown in FIG. 13A has an isoscelestrapezoidal shape whose upper base and lower base extend in the weldingdirection WD, but is a pattern resulting from vertically inverting theirradiation pattern 31 shown in FIG. 12A. As shown in FIG. 13B, in themain body 6 of the joint portion 5 obtained based on this irradiationpattern 31, for example, the first and second longitudinal portions 8, 9each have a shape similar to a straight line as compared with theirradiation pattern 31 (circular) shown in FIG. 6A. Further, each of theconnecting portions 10 has a linear shape. Furthermore, the intersectingportions 10 a are formed where the welded portion 4 constitutingadjacent connecting portions 10 intersects itself. That is, even in thisalternative, the plurality of connecting portions 10 form a grid-likestructure.

The irradiation pattern 31 shown in FIG. 14A has an isoscelestrapezoidal shape whose upper base and lower base extend in thedirection orthogonal to the welding direction WD, and the upper base isoriented downstream in the welding direction WD. As shown in FIG. 14B,the connecting portions 10 included in the main body 6 of the jointportion 5 obtained based on this irradiation pattern 31 include curvedportions 10 b having an approximately inverted C-shape and linearportions 10 c in this example. The curved portions 10 b and the linearportions 10 c are alternately arranged in the welding direction WD. Thecurved portions 10 b protrude in the welding direction WD. The curvedportions 10 b each correspond to the upper base and both oblique sidesof the ellipse of the irradiation pattern 31, and the linear portions 10c each correspond to the lower base of the ellipse of the irradiationpattern 31. Further, the intersecting portions 10 a are formed where thewelded portion 4 constituting adjacent connecting portions 10, that is,the welded portion 4 constituting the curved portions 10 b and thewelded portion 4 constituting the linear portions 10 c adjacent to thecurved portions 10 b intersect. That is, even in this alternative, theplurality of connecting portions 10 form a grid-like structure.

The irradiation pattern 31 shown in FIG. 15A has an isoscelestrapezoidal shape whose upper base and lower base extend in thedirection orthogonal to the welding direction WD, and the lower base isoriented downstream in the welding direction WD. As shown in FIG. 15B,the connecting portions 10 included in the main body 6 of the jointportion 5 obtained based on this irradiation pattern 31 include curvedportions 10 b having an approximately inverted C-shape and linearportions 10 c in this example. The curved portions 10 b and the linearportions 10 c are alternately arranged in the welding direction WD. Thecurved portions 10 b protrude in a direction opposite to the weldingdirection WD. Further, the intersecting portions 10 a are formed wherethe welded portion 4 constituting adjacent connecting portions 10, thatis, the welded portion 4 constituting the curved portions 10 b and thewelded portion 4 constituting the linear portions 10 c adjacent to thecurved portions 10 b intersect. That is, even in this alternative, theplurality of connecting portions 10 form a grid-like structure.

The irradiation pattern 31 shown in FIG. 16A has a figure eight shape.As shown in FIG. 16B, in the main body 6 of the joint portion 5 obtainedbased on this irradiation pattern 31, each of the connecting portions 10includes curved ends connected to the first and second longitudinalportions 8, 9, and a center portion has an approximately linear shape.Further, the intersecting portions 10 a are formed where the weldedportion 4 constituting adjacent connecting portions 10 intersectsitself. That is, even in this alternative, the plurality of connectingportions 10 form a grid-like structure. An outer circumferential portionof the figure eight shape may have an elliptical shape.

As in FIG. 14A, the irradiation pattern 31 shown in FIG. 17A has anisosceles trapezoidal shape whose upper base and lower base extend inthe direction orthogonal to the welding direction WD, and the upper baseis oriented downstream in the welding direction WD. With reference toFIG. 17A together with FIG. 17B, in this example, the speed Vw at whichthe irradiation pattern 31 moves is set equal to the speed Vp1 at whichthe virtual irradiation position P1 moves on the irradiation pattern 31to cause the connecting portions 10 included in the main body 6 of thejoint portion 5 to include first curved portions 10 d that protrude at arelatively acute angle in the welding direction WD and second curvedportions 10 e that protrude at a relatively obtuse angle in thedirection opposite to the welding direction WD. One intersecting portion10 a is formed by a tip of the first curved portion 10 d and the secondcurved portion 10 e adjacent to the first curved portion 10 d.

The irradiation pattern 31 shown in FIG. 18A is the same as that shownin FIG. 17A. Further, with reference to FIG. 18A together with FIG. 18B,in this example, the speed Vw at which the irradiation pattern 31 movesis set equal to the speed Vp1 at which the virtual irradiation positionP1 moves on the irradiation pattern 31 to cause the connecting portions10 included in the main body 6 of the joint portion 5 to include thefirst curved portions 10 d that protrude at a relatively acute angle inthe welding direction WD and the second curved portions 10 e thatprotrude at a relatively obtuse angle in the direction opposite to thewelding direction WD. Two intersecting portions 10 a are formed by aportion near the tip of the first curved portion 10 d and the secondcurved portion 10 e adjacent to the first curved portion 10 d.

The irradiation pattern 31 shown in FIG. 19A includes four curvedprotruding portions 31 a that have the same shape and are arranged atequal angular intervals (90 degree intervals). With reference to FIG.19A together with FIG. 19B, in the main body 6 of the joint portion 5obtained based on this irradiation pattern 31, each of the connectingportions 10 includes a curve whose ends are connected to the first andsecond longitudinal portions 8, 9. Further, the intersecting portions 10a are formed where the welded portion 4 constituting two connectingportions 10 adjacent to each other intersects itself. That is, even inthis alternative, the plurality of connecting portions 10 form agrid-like structure. Further, each of the first and second longitudinalportions 8, 9 includes a curve that is wavy in the direction orthogonalto the welding direction WD.

As in FIGS. 14A, 17A, and 18A, the irradiation pattern 31 shown in FIG.20A has an isosceles trapezoidal shape whose upper base and lower baseextend in the direction orthogonal to the welding direction WD, and theupper base is oriented downstream in the welding direction WD. Withreference to FIG. 20A together with FIG. 20B, in this example, the speedVw at which the irradiation pattern 31 moves is set equal to the speedVp1 at which the virtual irradiation position P1 moves on theirradiation pattern 31 to cause the connecting portions 10 included inthe main body 6 of the joint portion 5 to include the first curvedportions 10 d that protrude in the welding direction WD and the secondcurved portions 10 e that protrude at a relatively obtuse angle in thedirection opposite to the welding direction WD. The first curvedportions 10 d each include a linear portion 10 f extending in adirection approximately orthogonal to the welding direction WD and apair of oblique-side portions 10 g extending obliquely to the weldingdirection WD. This causes one first curved portion 10 d and one secondcurved portion 10 e located on the downstream side in a weldingdirection WD and connected to the one first curved portion 10 d to forma shape similar to a trapezoid. Two intersecting portions 10 a areformed by a portion near the tip of the first curved portion 10 d andthe second curved portion 10 e adjacent to the first curved portion 10d.

The irradiation pattern 31 shown in FIG. 21A includes two wedge-shapedportions each increasing in width in the welding direction WD, that is,an outer wedge-shaped portion 31 b and an inner wedge-shaped portion 31c disposed on the inner side relative to the outer wedge-shaped portion31 b.

The outer wedge-shaped portion 31 b as a whole includes a pair ofoblique-side portions 31 d oblique to the welding direction WD and a tipportion 31 e that has an arc shape and connects the oblique-sideportions 31 d. The oblique-side portions 31 d each include a firstportion 31 f that linearly extends and has one end connected to the tipportion 31 e, a second portion 31 g that linearly extends and has oneend connected to the other end of the first portion 31 f, and a thirdportion 31 h having one end connected to the other end of the secondportion 31 g. In this example, an angle to the welding direction WD isgetting larger in the order of the second portion 31 g, the firstportion 31 f, and the third portion 31 h, and the third portion 31 hextends approximately in the welding direction WD. Further, in thisexample, the second portion 31 g is shorter than the first portion 31 fand the third portion 31 h.

The inner wedge-shaped portion 31 c includes a pair of oblique-sideportions 31 i extending linearly and obliquely to the welding directionWD and a tip portion 31 j that has an arc shape and connects theoblique-side portions 31 i. The tip portion 31 j of the innerwedge-shaped portion 31 c approximately coincides with the tip portion31 e of the outer wedge-shaped portion 31 b.

The oblique-side portions 31 d of the outer wedge-shaped portion 31 bare each connected to one of the oblique-side portions 31 i of the innerwedge-shaped portion 31 c adjacent to the oblique-side portion 31 d witha U-shaped portion 31 k having an arc shape interposed between theoblique-side portion 31 d and the oblique-side portion 31 i.

With reference to FIG. 21A together with FIG. 21B, in the main body 6 ofthe joint portion 5 obtained based on the irradiation pattern 31 shownin FIG. 21A, the first and second longitudinal portions 8, 9 are formedby a linear welding mark or welded portion 4 corresponding to the thirdportion 31 h of the oblique-side portion 31 d of the outer wedge-shapedportion 31 b of the irradiation pattern 31. The intersecting portions 8a, 9 a are formed by the welded portion 4 corresponding to a portionincluding a connecting portion between the second portion 31 g and thethird portion 31 h of the oblique-side portion 31 d and the weldedportion 4 corresponding to a portion including the U-shaped portion 31k.

The connecting portions 10 include two types of elements, that is, afirst connecting portion 10 h and a second connecting portion 10 i, inwhich the first and second connecting portions 10 h, 10 i arealternately arranged at intervals in the welding direction WD. The firstconnecting portion 10 h and the second connecting portion 10 i adjacentto each other do not intersect. That is, in this example, the firstlongitudinal portion 8, the second longitudinal portion 9, and theconnecting portions 10 (first and second connecting portions 10 h, 10 i)form a ladder-like structure in plan view.

Regarding the manufacturing apparatus 21 according to second and thirdembodiments to be described below, a structure or function of which nospecific description will be given is the same as the structure orfunction according to the first embodiment. In the drawings relating tothese embodiments, the same or similar elements are denoted by the samesymbols.

Second Embodiment

FIG. 22 shows a manufacturing apparatus 21 for a joint body according tothe second embodiment of the present invention.

The manufacturing apparatus 21 does not include the blank conveyingdevice 23 (see FIGS. 1 and 2), and the table 22 and the blank material 2held on the table 22 are fixed. The manufacturing apparatus 21 includesa linear motion device 41 that linearly moves the laser oscillationsystem 25 in the welding direction WD (indicated by an arrow LMD1), anda linear motion device 42 that linearly moves, in a similar manner, thehoop supplying device 24 in the welding direction WD (indicated by anarrow LMD2). The linear motion devices 41, 42 serve as a synchronousmotion unit according to the present invention.

The hoop material 20 is continuously supplied by the hoop supplyingdevice 24 from obliquely above the blank material 2. The laseroscillation system 25 and the hoop supplying device 24 move in thewelding direction WD at a speed synchronized with the supplying speed ofthe hoop material 20. Further, the irradiation direction of the laserlight 26 emitted from the laser oscillation system 25 is changed by theturning device 27 such that the virtual irradiation position P1 movesalong a specific irradiation pattern 31 (see FIGS. 6A, 8A, 9A, 10A, 11A,12A, 13A, 14A, 15A, 16A, 17A, 18A, 19A, 20A, and 21A). Through the aboveprocesses, the joint portion 5 is formed based on the irradiationpattern 31 (see FIGS. 6B, 8B, 9B, 10B, 11B, 12B, 13B, 14B, 15B, 16B,17B, 18B, 19B, 20B, and 21B). Note that the linear motion device 42applies, after the formation of the end portion 7 of the joint portion5, tension to the hoop material 20 to cut the hoop material 20.

Third Embodiment

FIG. 23 shows a manufacturing apparatus 21 for a joint body according tothe third embodiment of the present invention.

The manufacturing apparatus 21 does not include the blank conveyingdevice 23 (see FIGS. 1 and 2), and the table 22 and the blank material 2held on the table 22 are fixed. Further, the manufacturing apparatus 21does not include the hoop supplying device 24 (see FIGS. 1 and 2), andthe reinforcing material 3 that has been cut out is temporarily fixed tothe blank material 2 by a fixture 51. The reinforcing material 3 thathas been cut out may be temporarily fixed to the blank material 2 byspot welding or laser spot welding. The laser oscillation system 25 isfixedly held by a robot arm 52 a included in a robot 52 such that thelaser light 26 is projected downward. In particular, according to thepresent embodiment, the manufacturing apparatus 21 does not include theturning device 27 (see FIGS. 1 and 2), and the irradiation direction ofthe laser light 26 is constant.

The robot arm 52 a moves the laser oscillation system 25 in twodirections in a horizontal plane, that is, in an X direction and Ydirection, such that the irradiation position P0 moves along a desiredmain body 6 of the joint portion 5 (see FIGS. 6B, 8B, 9B, 10B, 11B, 12B,13B, 14B, 15B, 16B, 17B, 18B, 19B, 20B, and 21B).

FIG. 24 shows the joint body 1 manufactured by the manufacturingapparatus 21 according to the present embodiment. Since the reinforcingmaterial 3 that has been cut out is used rather than applying tension tothe hoop material 20 to cut the hoop material 20, the joint portion 5 ofthe joint body 1 includes only the main body 6 without the end portion7. Similarly, even when the joint body 1 is manufactured by themanufacturing apparatus 21 according to the first embodiment (FIGS. 4and 5) and the manufacturing apparatus according to the secondembodiment (FIG. 22), a configuration where the reinforcing material 3that has been cut out rather than the hoop material 20 that iscontinuously supplied is joined to the blank material 2 allows the jointportion 5 to include only the main body 6 without the end portion 7.

FIG. 25 shows an alternative of the joint body 1. In this alternative,the joint portion 5 is formed, based on the irradiation pattern 31 shownin FIG. 12A, at both ends of the reinforcing material 3, and the jointportion 5 is formed, based on the irradiation pattern 31 shown in FIG.9A, at portions other than both the ends of the reinforcing material 3.This causes the joint portion 5 to have, at both the ends of thereinforcing material 3, the same shape as shown in FIG. 12B and to have,at the portions other than both the ends of the reinforcing material 3,the same shape as shown in FIG. 9B. The irradiation pattern 31 shown inFIG. 12A is applied to both the ends of the reinforcing material 3 toprovide the welded portion 4 at the corners of the reinforcing material3, thereby further increasing the joint strength of the reinforcingmaterial 3 to the blank material 2. At least any two of the irradiationpatterns 31 shown in FIGS. 6A, 8A, 9A, 10A, 11A, 12A, 13A, 14A, 15A,16A, 17A, 18A, 19A, 20A, and 21A may be used in combination.

DESCRIPTION OF SYMBOLS

-   1 Joint body-   2 Blank material (first metal member)-   3 Reinforcing material (second metal member)-   4 Welded portion-   5 Joint portion-   6 Main body-   7 End portion-   8 First longitudinal portion-   8 a Intersecting portion-   9 Second longitudinal portion-   9 a Intersecting portion-   10 Connecting portion-   10 a Intersecting portion-   12 pillar-   20 Hoop material (second metal member)-   21 Manufacturing apparatus-   22 Table-   22 a Fixture-   23 Blank conveying device-   24 Hoop supplying device (supplying unit)-   24 a Supplying roll pair-   25 Laser oscillation system-   26 Laser light-   27 Turning device (irradiation direction changing unit)-   28 Cutting drive device-   29 Control device-   31 Irradiation pattern-   41, 42 Linear motion device-   51 Fixture-   52 Robot-   52 a Robot arm-   P0 Irradiation position-   P1 Virtual irradiation position-   A Direction (first direction)-   B Direction (second direction)-   C Direction-   WD Welding direction-   CD Conveying direction-   SD Supplying direction-   MD Motion direction-   LMD1 Linear motion direction-   LMD2 Linear motion direction-   AR1, AR2, AR3, AR4 Region

1. A joint body comprising: a first metal member; a second metal memberplaced on the first metal member; and a joint portion including a weldedportion where the first metal member and the second metal member arejoined together, the welded portion having a line shape, wherein thejoint portion includes: a first longitudinal portion extending in afirst direction, the first longitudinal portion having firstintersecting portions arranged in the first direction, the weldedportion intersecting itself at the first intersecting portions; a secondlongitudinal portion located apart from the first longitudinal portionin a second direction intersecting the first direction and extending inthe first direction, the second longitudinal portion having secondintersecting portions arranged in the first direction, the weldedportion intersecting itself at the second intersecting portions; and aplurality of connecting portions arranged in the first direction, eachextending in the second direction and connecting the first longitudinalportion and the second longitudinal portion.
 2. The joint body accordingto claim 1, wherein the plurality of connecting portions are arrangedapart from each other in the first direction, and the first longitudinalportion, the second longitudinal portion, and the plurality ofconnecting portions form a ladder-like structure.
 3. The joint bodyaccording to claim 1, wherein the plurality of connecting portions forma grid-like structure.
 4. A manufacturing method for a joint body havinga first metal member and a second metal member joined together bycausing a laser oscillation system to irradiate a surface of the secondmetal member placed on the first metal member with laser light to form ajoint portion including a welded portion where the first metal memberand the second metal member are joined together, the welded portionhaving a line shape, the manufacturing method comprising moving anirradiation position of the laser light to cause the joint portion toinclude: a first longitudinal portion extending in a first direction,the first longitudinal portion having first intersecting portionsarranged in the first direction, the welded portion intersecting itselfat the first intersecting portions; a second longitudinal portionlocated apart from the first longitudinal portion in a second directionintersecting the first direction and extending in the first direction,the second longitudinal portion having second intersecting portionsarranged in the first direction, the welded portion intersecting itselfat the second intersecting portions; and a plurality of connectingportions arranged in the first direction, each extending in the seconddirection and connecting the first longitudinal portion and the secondlongitudinal portion.
 5. The manufacturing method for a joint bodyaccording to claim 4, wherein the laser oscillation system is moved inthe welding direction relative to the first and second metal memberswith an irradiation direction of the laser light being periodicallychanged, so that, assuming that the laser oscillation system is not inmotion in a welding direction relative to the first and second metalmembers, the irradiation portion is moved along a closed figure.
 6. Themanufacturing method for a joint body according to claim 5, wherein thesecond metal member is a hoop material, the first metal member isconveyed in a conveying direction opposite to the welding direction, andthe second metal member is continuously supplied in a supplyingdirection that coincides with the conveying direction while beingpressed against the first metal member, and the irradiation direction ofthe laser light emitted from the laser oscillation system isperiodically changed to move the irradiation position along the closedfigure with a position of the laser oscillation system fixed.
 7. Themanufacturing method for a joint body according to claim 5, wherein thesecond metal member is a hoop material, a position of the first metalmember is fixed, the second metal member is continuously supplied whilebeing pressed against the first metal member, and a source of supply ofthe second metal member and the laser oscillation system are moved inthe welding direction at a speed synchronized with a supplying speed ofthe second metal member, and the irradiation direction of the laserlight emitted from the laser oscillation system is periodically changedto move the irradiation position along the closed figure.
 8. Themanufacturing method for a joint body according to claim 5, wherein areference speed is defined for movement of the irradiation positionalong the closed figure, when the irradiation position moves in thewelding direction, a speed at which the irradiation position moves alongthe closed figure is set equal to a first correction speed lower thanthe reference speed, and when the irradiation position moves in adirection opposite to the welding direction, the speed at which theirradiation position moves along the closed figure is set equal to asecond correction speed higher than the reference speed.
 9. Themanufacturing method for a joint body according to claim 4, wherein thesecond metal member is placed on and temporarily fixed to the firstmetal member, and the laser oscillation system is moved in twodirections within a horizontal plane to move the irradiation position ofthe laser light along the welded portion constituting the joint portion.10. The manufacturing method for a joint body according to claim 4,wherein the irradiation position of the laser light is moved forward andbackward in a zigzag-line shape in a direction intersecting the weldingdirection, and tension is applied to the second metal member to cut thesecond metal plate.
 11. A manufacturing apparatus for a joint bodyhaving a first metal member and a second metal member joined together bycausing a laser oscillation system to irradiate a surface of the secondmetal member placed on the first metal member with laser light to form ajoint portion including a welded portion where the first metal memberand the second metal member are joined together, the welded portionhaving a line shape, the manufacturing apparatus comprising anirradiation position motion unit configured to move an irradiationposition of the laser light to cause the joint portion to include: afirst longitudinal portion extending in a first direction, the firstlongitudinal portion having first intersecting portions arranged in thefirst direction, the welded portion intersecting itself at the firstintersecting portions; a second longitudinal portion located apart fromthe first longitudinal portion in a second direction intersecting thefirst direction and extending in the first direction, the secondlongitudinal portion having second intersecting portions arranged in thefirst direction, the welded portion intersecting itself at the secondintersecting portions; and a plurality of connecting portions arrangedin the first direction, each extending in the second direction andconnecting the first longitudinal portion and the second longitudinalportion.
 12. The manufacturing apparatus for a joint body according toclaim 11, wherein the laser oscillation system is moved in the weldingdirection relative to the first and second metal members withirradiation positon motion unit periodically changing an irradiationdirection of the laser light, so that, assuming that the laseroscillation system is not in motion in a welding direction relative tothe first and second metal members, the irradiation potion is movedalong a closed figure.
 13. The manufacturing apparatus for a joint bodyaccording to claim 12, wherein the second metal member is a hoopmaterial, a position of the laser oscillation system is fixed, and theirradiation position motion unit includes: a conveying unit configuredto convey the first metal member in a conveying direction opposite tothe welding direction; a supplying unit configured to continuouslysupply the second metal member in a supplying direction that coincideswith the conveying direction while pressing the second metal memberagainst the first metal member; and an irradiation direction changingunit configured to periodically change the irradiation direction of thelaser light emitted from the laser oscillation system to move theirradiation position along the closed figure.
 14. The manufacturingapparatus for a joint body according to claim 12, wherein the secondmetal member is a hoop material, a position of the first metal member isfixed, and the irradiation position motion unit includes: a supplyingunit configured to continuously supply the second metal member whilepressing the second metal member against the first metal member; asynchronous motion unit configured to move the supplying unit and thelaser oscillation system in the welding direction at a speedsynchronized with a supplying speed of the second metal member; and anirradiation direction changing unit configured to periodically changethe irradiation direction of the laser light emitted from the laseroscillation system to move the irradiation position along the closedfigure.
 15. The manufacturing apparatus for a joint body according toclaim 13, wherein a reference speed is defined for movement of theirradiation position along the closed figure, when the irradiationposition moves in the welding direction, a speed at which theirradiation position moves along the closed figure is set equal to afirst correction speed lower than the reference speed, and when theirradiation position moves in a direction opposite to the weldingdirection, the speed at which the irradiation position moves along theclosed figure is set equal to a second correction speed higher than thereference speed.
 16. The manufacturing apparatus for a joint bodyaccording to claim 11, wherein the second metal member is placed on andtemporarily fixed to the first metal member, and the irradiationposition motion unit moves the laser oscillation system in twodirections within a horizontal plane to move the irradiation position ofthe laser light along the welded portion constituting the joint portion.17. The manufacturing apparatus for a joint body according to claim 11,wherein the irradiation position motion unit moves the irradiationposition of the laser light forward and backward in a zigzag-line shapein a direction intersecting the welding direction and applies tension tothe second metal member to cut the second metal plate.